1. Field of the Invention
The present invention relates to a getter flashing method for a cathode ray tube (CRT) and a getter for conducting the same, and more particularly, to a getter flashing method using a getter loaded with an active metal such that the active metal is vaporized and diffused toward an inner surface of the funnel in the vicinity of the getter, thereby preventing deterioration in brightness and occurrence of a color bar.
2. Description of the Related Art
Generally, in the CRT manufacturing process, the getter flashing operation is performed after the gas or air exhausting step in order to make the inside of the CRT to be in a high vacuum state.
FIG. 5 is a cross sectional view of a CRT illustrating the conventional getter flashing method. As shown in FIG. 5, the getter 10 has a cup-shaped receptacle 14 for receiving an active metal such as barium and magnesium, and a band-shaped support 12 an upper end of which is connected to the receptacle 14 to support it. A bottom end of the support 12 is fixed on an electron gun 8.
In the conventional getter flashing method, the getter 10 is placed on the inside of the CRT such that the opening portion of the receptacle 14 faces a shadow mask 6. And a high-frequency induction heating coil 18 is installed on the outside of a funnel 2 adjacent to the receptacle 14, and, during the getter flashing operation, applied with a high-frequency induced voltage for a predetermined time. In such a way, the active metal contained in the receptacle 14 is abruptly heated and vaporized. When the vaporized metal condenses, it absorbs residual gases such as hydrogen, carbon dioxide and oxygen to remove them.
However, in the aforementioned conventional method, the vaporized active metal is diffused toward the shadow mask 6 during the getter flashing operation because the opening portion of the receptacle 14 containing the active metal is directed toward the shadow mask 6. As a result, the vaporized metal passing through beam-guide holes of the shadow mask 6 is deposited on a phosphor layer 5 coated on a panel 4, causing discoloration and deterioration in brightness.
Particularly in the mini CRTs such as a 10 inch or 6 inch CRT, a rainbow-shaped color bar appears on the screen because the vaporized active metal is largely deposited on the shadow mask due to the short distance between the getter and shadow mask.